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Quantum chemical studies of carbon-based graphene-like nanostructures: from benzene to coronene.
J Mol Model
January 2025
Department of Chemistry, Federal Institute of Education, Science and Technology of Espírito Santo, Av. Min. Salgado Filho, Vila Velha, 29106-010, Espírito Santo, Brazil.
Context: This study presents quantum chemical analysis of 14 distinct carbon-based nanostructures (CBN), ranging from simple molecules, like benzene, to more complex structures, such as coronene, which serves as an exemplary graphene-like model. The investigation focuses on elucidating the relationships between molecular orbital (MO) energies, the energy band gaps, electron occupation numbers (eON), electronic conduction, and the compound topologies, seeking to find the one that approaches most of a graphene-like structure for in silico studies. Through detailed examination of molecular properties including chemical hardness and chemical potential, we demonstrate that the electronic exchange between orbitals is directly influenced by the structural topology of the carbon-based nanostructures, as the electron occupation numbers and the molecular orbital energies.
View Article and Find Full Text PDFUltrasound B-Scan for Posterior Segment and Extraocular Evaluation in Ocular Cysticercosis.
Clin Ophthalmol
January 2025
University Eye Clinic Maastricht, Maastricht, The Netherlands.
Purpose: Cysticercosis, caused by Taenia solium larvae, can affect various ocular and extraocular structures, leading to significant morbidity. Ultrasound B-scan imaging plays a pivotal role in diagnosing and classifying cysticercosis lesions. The aim of the study was to describe the ultrasound B-scan characteristics of ocular and extraocular cysticercosis, proposing a classification system based on anatomical localization to enhance understanding and management.
View Article and Find Full Text PDFKDiffered brain spontaneous neural activity between limb-onset and bulbar-onset amyotrophic lateral sclerosis patients.
Brain Res Bull
January 2025
Department of Geriatrics, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China. Electronic address:
Purpose: To investigate the differences in brain spontaneous neural activity between limb-onset and bulbar-onset amyotrophic lateral sclerosis (ALS-L and ALS-B, respectively) patients using resting-state functional MRI (rs-fMRI) with amplitude of low-frequency fluctuation (ALFF) and regional homogeneity (ReHo).
Materials And Methods: The rs-fMRI data were collected from 41 ALS patients (11 ALS-B and 30 ALS-L) and 25 healthy controls (HC). ALFF and ReHo values were calculated, and group differences were assessed using one-way ANCOVA and two-sample t-tests.
Electronic quenching of sulfur induced by argon collisions.
Phys Chem Chem Phys
January 2025
Univ Rennes, CNRS, IPR (Institut de Physique de Rennes) - UMR 6251, F-35000 Rennes, France.
An accurate potential energy model, explicitly designed for studying scattering and treating the spin-orbit and nonadiabatic couplings on an equal footing, is proposed for the S + Ar system. The model is based on the Effective Relativistic Coupling by Asymptotic Representation (ERCAR) approach, building the geometry dependence of the spin-orbit interaction a diabatisation scheme. The resulting full diabatic model is used in close-coupling calculations to compute inelastic scattering cross sections for de-excitation from the S(D) fine structure level into the P multiplet.
View Article and Find Full Text PDFWhy does silicon have an indirect band gap?
Mater Horiz
January 2025
Department of Materials Science, University of Michigan, Ann Arbor, Michigan 48109, USA.
It is difficult to intuit how electronic structure features-such as band gap magnitude, location of band extrema, effective masses, -arise from the underlying crystal chemistry of a material. Here we present a strategy to distill sparse and chemically-interpretable tight-binding models from density functional theory calculations, enabling us to interpret how multiple orbital interactions in a 3D crystal conspire to shape the overall band structure. Applying this process to silicon, we show that its indirect gap arises from a competition between first and second nearest-neighbor bonds-where second nearest-neighbor interactions pull the conduction band down from Γ to X in a cosine shape, but the first nearest-neighbor bonds push the band up near X, resulting in the characteristic dip of the silicon conduction band.
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